Plasma clearances of branched-chain amino acids in control subjects and in patients with cirrhosis

Marchesini, Giulio; Bianchi, Giampaolo; Vilstrup, Hendrik; Checchia, Giovanni Antonio; Patrono, Daniela; Zoli, Marco

doi:10.1016/s0168-8278(87)80017-x

Cited by 55 publications

(27 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, in the kidney the Tyr production rate plus appearance from protein breakdown (7.0 Ϯ 1.5 mol͞min) is greater than its disposal rate (1.8 Ϯ 1.0 mol͞min), resulting in a net release of Tyr from the kidney during the postabsorption state. Of note, in patients with cirrhosis, circulating Tyr concentrations are higher than in healthy control subjects (29) because of the greater impact the liver has on the Tyr disposal rate than on Tyr production (Phe conversion to Tyr). Theoretically, renal failure should have little impact on the Tyr disposal rate if the liver is functioning normally but will have relatively higher impact on Tyr production and appearance in the systemic circulation.…”

Section: Discussionmentioning

confidence: 97%

The kidney is an important site for in vivo phenylalanine-to-tyrosine conversion in adult humans: A metabolic role of the kidney

Møller

Meek

Bigelow

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Synthesis of Tyr in the human body occurs by hydroxylation of the indispensable amino acid Phe. Until now, it was believed that in humans, this process was restricted to the liver, but we provide compelling evidence of production of Tyr from Phe in the kidney. To determine whether the human kidney produces Tyr, we measured Tyr balance, the Tyr appearance rate, and the Phe-to-Tyr conversion in 12 healthy human subjects by using [ 15 N]Phe and [ 2 H4]Tyr as tracers. Renal plasma flow was measured by using paraaminohippurate, and sampling from the femoral artery and renal veins was performed. The results were compared with those obtained in 12 control subjects undergoing hepatic vein catheterization and infusion of identical tracers. In all 12 subjects, there was a net uptake of Phe by the kidney (2.2 ؎ 1.2 mol͞min), whereas Tyr was released (5.3 ؎ 1.5 mol͞min). In contrast, there was a net uptake of both Phe (9.5 ؎ 1.2 mol͞min) and Tyr (14.3 ؎ 1.3 mol͞min) by the splanchnic bed. Phe conversion to Tyr occurred at a rate of 5.2 ؎ 1.2 mol͞min in kidney and 3.0 ؎ 0.7 mol͞min in the splanchnic bed. The kidney contributed a substantial amount of Tyr to the systemic circulation where the splanchnic bed was a net remover of Tyr. Our results demonstrate that the kidney is the major donor of Tyr to the systemic circulation by its conversion of Phe to Tyr. This observation may have important clinical implications for patients with both renal and hepatic disease, who may be at risk of Phe overloading and Tyr deficiency, and it should be considered when parenteral or enteral nutrients are administered rich in Phe and low in Tyr.

show abstract

Section: Discussionmentioning

confidence: 97%

The kidney is an important site for in vivo phenylalanine-to-tyrosine conversion in adult humans: A metabolic role of the kidney

Møller

Meek

Bigelow

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Plasma amino acid concentrations were determined with a 3A30 Carlo Erba Amino Analyser (Carlo Erba-Fisons, Rodano, Milan, Italy), using the method described previously. 27 All the samples of each subject were run within the same assay. In our laboratory, the intraassay and inter-assay coef®cients of variation in the determination of plasma amino acids were within AE 5% and AE 10%, respectively.…”

Section: Methodsmentioning

confidence: 99%

Effects of hyperglycaemia and hyperinsulinaemia on plasma amino acid levels in obese subjects with normal glucose tolerance

et al. 2000

View full text Add to dashboard Cite

OBJECTIVE: To investigate the effects of hyperglycaemia and hyperinsulinaemia on amino acid disposal in human obesity. DESIGN: Four sequential experimental conditions: (1) overnight fasting; (2) hyperglycaemia with hyperinsulinaemia (2 h hyperglycaemic clamp at 11 mmolal); (3) hyperglycaemia with basal insulin (1 h hyperglycaemic clamp during somatostatin infusion), (4) hyperglycaemia with resuming hyperinsulinaemia (1 h hyperglycaemic clamp after somatostatin discontinuation). SUBJECTS: Seven non-obese and seven obese non-diabetic, normo-insulinaemic subjects. MEASUREMENTS: Glucose infused to maintain steady-state hyperglycaemia. Plasma insulin, glucagon, free fatty acid and amino acid concentrations in the last 20 min of the four experimental conditions. Net rates of plasma amino acid disappearance and appearance (m mmolal per hour), calculated as the slopes of the regression of amino acid concentration on time. RESULTS: The amount of glucose infused to maintain hyperglycaemia was reduced by nearly 50% in obese subjects. During hyperinsulinaemia, FFA suppression was lower in obese subjects. In all experimental conditions plasma amino acid levels were slightly, non-signi®cantly higher in obese than in non-obese subjects. In both groups plasma amino acids decreased slightly with ongoing fasting, decreased remarkably during hyperglycaemia ± hyperinsulinaemia, rose promptly when insulin concentration was suppressed by somatostatin infusion, and declined again after somatostatin discontinuation. Also the time-course of plasma branched-chain amino acids, which paralleled that of total amino acids, was similar in the two groups. The net rates of amino acid disappearance from plasma did not differ in obese and non-obese subjects both at fasting and during hyperglycaemia ± hyperinsulinaemia. Also plasma amino acid appearance during hyperglycaemia with basal insulin was not different in the two groups. CONCLUSION: The net traf®c of amino acids to and from plasma in relation to insulin drive and prevailing glucose is not impaired in obese subjects with normal glucose tolerance, in spite of a decreased insulin sensitivity of glucose and lipid metabolism.

show abstract

“…All administrations of Tarvil ® and placebo took place at the same time of the day (around 10 a.m.). The period of time between tests and the fasting period before tests were chosen to minimize any potential carryover effects as BCAA have a half-life of about 1.5 h and take approximately 8 h to clear (Marchesini et al 1987).…”

Section: Experimental Design and General Proceduresmentioning

confidence: 99%

Emotion-based decision-making in healthy subjects: short-term effects of reducing dopamine levels

et al. 2006

View full text Add to dashboard Cite

show abstract

Plasma clearances of branched-chain amino acids in control subjects and in patients with cirrhosis

Cited by 55 publications

References 28 publications

The kidney is an important site for in vivo phenylalanine-to-tyrosine conversion in adult humans: A metabolic role of the kidney

The kidney is an important site for in vivo phenylalanine-to-tyrosine conversion in adult humans: A metabolic role of the kidney

Effects of hyperglycaemia and hyperinsulinaemia on plasma amino acid levels in obese subjects with normal glucose tolerance

Emotion-based decision-making in healthy subjects: short-term effects of reducing dopamine levels

Contact Info

Product

Resources

About